When is Medical Evidence Necessary in Pennsylvania to Show Causation?

Do You Know the Rule?

In Pennsylvania, a workers’ compensation claimant has to prove that he sustained an injury. He also needs to show that his job caused the injury. Because the employee bears the burden of proof to show that causal link, he may have to provide expert medical testimony.

Does a worker need medical evidence to show causation when it’s obvious?

No. When the causal relationship is obvious, no medical evidence is required to show that the job caused the injury. 

Generally, where an employee is doing an act as part of his job that requires force or strain and pain is experienced at the point of force or strain, the connection is obvious. This is because pain is a clear symptom of an injury. 

Another way to put this is that the relationship between the job and injury is obvious if the injury immediately manifests itself while the claimant is performing a work task, the nature of which can cause the injury. For example, the connection is likely clear when a furniture store employee grabs his back in pain after bending over to lift one side of a couch.

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The key feature of obviousness is that it involves a connection that is clear enough that an untrained layperson would have no problem making the connection between the job and the injury, or the injury and the disability.

What if the cause is not obvious?

If the causal relationship between the work and injury, or work injury and disability, is not obvious, then the employee has to establish that relationship with “unequivocal” medical testimony.

What does “unequivocal” mean?

Medical testimony is considered unequivocal if the medical expert, after establishing a proper foundation, testifies within his professional opinion that a certain fact or condition exists.

What are some case examples where the job obviously caused the injury?

A registered nurse was moving a large patient when he felt something pop in his back, experienced immediate pain, and mentioned it to his co-worker. Northwest Medical Center v. WCAB, No. 409 C.D. 2005 (Pa. Commw. Ct. 07/08/05).

A baker-in-training suddenly developed a rash on her face, neck, and arms, accompanied with mild shortness of breath, while in the third hour of her regularly scheduled shift in the bakery department. Giant Eagle, Inc. v. Workers’ Compensation Appeal Bd., No. 725 A.2d 873 (Pa. Commw. Ct. 1999).

What are some case examples where it was not obvious that the job caused the injury?

The employee worked for a metals fabricator and had smoked cigarettes for more than 30 years when she started. She claimed that exposure at work to harsh substances, such as acetone and a nickel alloy, used to treat metal, caused her lung injuries. Nagi v. Medplast Engineered Products, Inc., No. 391 C.D. 2023 (Pa. Commw. Ct. 07/10/25).

A psychiatric assistant claimed that she became disabled as a result of injury she sustained two months earlier when she had to physically restrain a patient with a blanket for 2.5 hours. Albert Einstein Healthcare v. WCAB , No. 2189 C.D. 2007 (Pa. Commw. Ct. 04/04/08).

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